(1) Field of the Invention
The present invention generally relates to a cooling system, and particularly to a cooling system for a projector.
(2) Description of the Related Art
A projector has many kinds of heat source devices generating high heat. For example, the heat source device can be a light source device, a printed circuit board assembly, or a power supply system. Therefore, it is an important issue to cool the projector.
Please refer to FIG. 1. A cooling system 4 for a conventional projector 2 includes a plurality of fans 10, a thermal sensor 12 and a control module 14. The fans 10 are used for generating an air flow for dissipating heat generated by a heat source device 3 within the projector 2. The thermal sensor 12 is disposed near an air inlet 5 of the projector 2 to sense an environmental temperature.
The control module 14 includes a storage device 1402. A relationship F01 between the environmental temperature range and the voltage of the fan 10 is stored in the storage device 1402. For example, when the temperature is between 27° C. and 29° C., the voltage of the fan is controlled in 9V. When the temperature is between 20° C. and 31° C., the voltage of the fan is controlled in 10V. When the temperature is between 31° C. and 33° C., the voltage of the fan is controlled in 11V.
After the thermal sensor 12 senses the environmental temperature and looks up the temperature range in the relationship F01 pre-stored in the storage device 1402 to find a voltage corresponding to the environmental temperature. The control module 14 drives the fans 10 and controls the rotation speed of the fans 10 by the voltage corresponding to the environmental temperature. For example, after sensing the environmental temperature being 30° C., the thermal sensor 12 looks up the temperature range in the relation F01 pre-stored in the storage device 1402 to find a voltage, 10V, corresponding to the environmental temperature. Then, the control module 14 drives the fans 10 by the voltage in 10V.
However, the above method causes a lot of problems. For example, when the conventional projector 2 is used at a place with low air pressure, such as a high mountain, the cooling effect is poor. If the voltage is still provided according to the temperature range, the rotation speed of the fans 10 is relatively insufficient to cool the conventional projector 2. Practically, the rotation speed of the fans 10 increases and decreases by turns without obtaining ideal cooling effects. To solve this problem, a pressure sensor 13 sensing variations in air pressure is provided in the conventional projector 2 to adjust the voltage controlling the fans 10. However, a producing cost is increased greatly. Furthermore, when the fans 10 are on the end of the lifetime or piles up dust to decrease the cooling efficiency of the cooling system 4, the predetermined voltage is insufficient for dissipating heat within the conventional projector 2.
Moreover, when the heat source devices generates heat suddenly, the thermal sensor 12 is only able to sense the environmental temperature without sensing the temperature near the heat source devices. As a result, the rotation speed of the fans 10 is not changed, and the heat source devices can not be cooled. Thus, the method for controlling the voltage of the fans 10 by utilizing the thermal sensor 12 disposed near the air inlet 5 to sense the environmental temperature can not sense the temperature of the heat source device 3 in the projector 2. The heat source device 3 can not be cooled properly.
Therefore, the objective of the present invention is providing a cooling system for a projector to solve the above problem.